FAA Calls For Check Of Drag Brace Lower Lock Link On Boeing 787 Landing Gear

The Federal Aviation Administration (FAA) has warned that a specific inspection process was not completed during the manufacturing process of the drag brace lower lock link assemblies for the Boeing 787’s main landing gear (MLG), mandating operators to either check maintenance records or inspect whether certain drag brace lower links were installed on the aircraft.

The regulator issued the airworthiness directive (AD) despite one airline saying that a requirement bulletin (RB) was sufficient.

Skipping inspections

The directive read that a report outlined that during the manufacturing process of drag brace lower lock link assemblies for the MLG of the 787-8, 787-9, and 787-10, a certain mandatory inspection was not performed, prompting the FAA to issue the AD.

As a result, the FAA issued the AD, mandating a maintenance record check or inspecting the MLG’s drag brace lower lock link assembly for affected part serial numbers, outlined in Boeing Alert RB B787-81205-SB320048-00, which the manufacturer issued on November 20, 2023.

The RB’s recommended compliance time was to conduct the inspections within 48 months after it issued the bulletin or within 48 months after the original airworthiness certificate was issued for a potentially affected 787, whichever occurs later.

If airlines find that one of their drag brace lower lock link assembly have one of the four affected part serial numbers, they have to replace the part within 48 months after November 20, 2023, or within 48 months after an original standard airworthiness certificate was issued, whichever occurs later.

Unnecessary directive

The FAA’s notice of proposed rulemaking (NPRM) preceded the directive. Since the regulator published the notice on August 1, four stakeholders commented on the proposed rulemaking, including one individual, who supported it without further changes.

American Airlines, United Airlines, and Boeing pointed out that the directive had a typo regarding one of the assembly’s serial numbers, which the FAA agreed to amend once it published the final rule AD.

However, American Airlines also argued that the directive was unnecessary since the safety issue was being addressed via the RB.

According to the carrier, compliance with the directive burdens airlines and maintenance, overhaul, and repair (MRO) organizations with creating safeguards to look for the quartet of serial numbers any time maintenance is performed on the 787’s drag brace lower lock link assemblies and the aircraft throughout its remaining life of the entire global Dreamliner fleet.

“The FAA disagrees with the request to withdraw the NPRM. Operators are not required to accomplish Boeing Alert Requirements Bulletin B787-81205-SB320048-00 RB, Issue 001, dated November 20, 2023, until an AD mandates accomplishment.”

The regulator added that the directive addresses an unsafe condition by mandating the removal and prohibiting the installation of the potentially affected parts on the 787.

“In addition, due to rotability of the affected parts, the parts installation prohibition specified in […] this AD is the only way to ensure the affected parts are not installed on all airplanes identified in […] of this AD.”

According to the FAA, undetected cracks could lead to a fracture of the drag brace lower lock link assembly, potentially resulting in the MLG’s collapse and subsequent loss of directional control while the aircraft is on the ground. The regulator’s worst-case scenario pointed to a potential runway excursion and wing box fuel tank penetration.

Affecting even the latest 787s

Boeing’s RB outlined that 787s with line number (LN) between 6 and 1168 were affected by the bulletin, mandating the inspections and/or maintenance checks. Ch-aviation data showed that LN 1168 was a Korean Air 787-10, which operated its first flight on September 7, 2024, with a preliminary delivery date in December.

The FAA estimated that the directive potentially affected 156 aircraft of the type. An inspection or records check will set back operators $85 per aircraft (covering one work hour, estimated at $85 per hour).

If the assembly has to be replaced, the regulator estimated that it would take 18 working hours. In combination with part expenses of $39,119, the approximate cost per aircraft to replace it would be $40,649 per aircraft. The AD’s effective date is December 31, 2024.